U.S. Pat. No. 3,260,808 entitled "Electric Switch with Lockable Rotary Operator" described a circuit breaker that provides rotary operation to a circuit breaker operating handle. The handle can be locked in its OFF position to allow an operator to work on the associated electric equipment without danger of the circuit breaker handle being inadvertently turned ON to electrically energize the equipment.
In extreme circumstances, such as described in U.S. Pat. No. 4,978,816, the circuit breaker contacts could become welded together in their closed condition. When the circuit breaker operating handle is later moved to the reset position, the circuit breaker contacts could conceivably remain welded together. Locking the circuit breaker handle could then erroneously indicate to an operator that the associated equipment is electrically de-energized.
One purpose of this invention is to describe a rotary handle operator that allows positive ON indication by preventing the circuit breaker operating handle from being locked in the OFF position unless the circuit breaker contacts are in their open condition.